﻿// Copyright (c) Brock Allen & Dominick Baier. All rights reserved.
// Licensed under the Apache License, Version 2.0. See LICENSE in the project root for license information.


using System;

namespace IdentityModel
{
  /// <summary>Extensions for converting epoch/unix time to DateTime and DateTimeOffset</summary>
  public static class EpochTimeExtensions
  {
    /// <summary>Converts the given date value to epoch time.</summary>
    public static long ToEpochTime(this DateTime dateTime)
    {
      var date = dateTime.ToUniversalTime();
      var ticks = date.Ticks - new DateTime(1970, 1, 1, 0, 0, 0, 0, DateTimeKind.Utc).Ticks;
      var ts = ticks / TimeSpan.TicksPerSecond;
      return ts;
    }

    /// <summary>Converts the given date value to epoch time.</summary>
    public static long ToEpochTime(this DateTimeOffset dateTime)
    {
      var date = dateTime.ToUniversalTime();
      var ticks = date.Ticks - new DateTimeOffset(1970, 1, 1, 0, 0, 0, TimeSpan.Zero).Ticks;
      var ts = ticks / TimeSpan.TicksPerSecond;
      return ts;
    }

    /// <summary>Converts the given epoch time to a <see cref="DateTime"/> with <see cref="DateTimeKind.Utc"/> kind.</summary>
    public static DateTime ToDateTimeFromEpoch(this long intDate)
    {
      var timeInTicks = intDate * TimeSpan.TicksPerSecond;
      return new DateTime(1970, 1, 1, 0, 0, 0, 0, DateTimeKind.Utc).AddTicks(timeInTicks);
    }

    /// <summary>Converts the given epoch time to a UTC <see cref="DateTimeOffset"/>.</summary>
    public static DateTimeOffset ToDateTimeOffsetFromEpoch(this long intDate)
    {
      var timeInTicks = intDate * TimeSpan.TicksPerSecond;
      return new DateTimeOffset(1970, 1, 1, 0, 0, 0, TimeSpan.Zero).AddTicks(timeInTicks);
    }
  }
}